Halogenated indigo and process of making.



UNITED STATES PATENT ornrcn.

HAFEN-QIl' THE-RHINE, GERMANY, ASSIGNORS 'IO BADISCHE ANILIN 8a SODA FABRIK, OF LUDWIGSHAFEN-ON-THE-RHINE, GERMANY, A CORPORATION.

HALOGENATED INDIGO AND rnocnss or MAKING.

No Drawing.

To all whom it may concern:

Be .it known that we, PAUL ERWIN OBER- nnrr, Ih. D., Vm'ron VILLIGER, Ph. D., and PAUL NAWIASKY, Ph. D., chemists, subjects the first and third, respectively, of the King of Saxony and the Emperor of Austria- Hungary, the second a citizen of the Swiss Republic, residing at Ludwigshafen-on the- Rhine, Germany, have invented new and useful Improvements in Halogenated Indigo and Processes of Making Same, of which the following is a specification.

Our invention relates to the production of a new tetra-halogenated indigo, namely 7.7-dichlor-5.5-dibrom-indigo.

\Ve can prepare our new tetra-halogen indigo by the saponification and oxidation of the methyl ester of 7 -chlor-5-brom-indoxylcarboxylic acid. 4 Our new 7.7-dichlor-5.5-dibrom-indigo is characterized by possessing the following properties. It dyes cotton blue and yields a blue solution in cold concentrated sulfuric acid. It is soluble in boiling dimethyl anilin, and on being oxidized with concentrated nitric acid in concentrated sulfuric acid solution it yields 3-chlor-5-brom-isatoic acid, which acid melts and decomposes at about 260 C.

The following example will serve to illustrate further the nature of our invention, which, however, is not confined to this example. The parts are by weight.

llxample: Introduce, while stirring, three hundred and thirty-six and one half parts of the methyl ester of 4-brom-6-chlorpheiiyl-glycin-2-carboxylic acid (obtainable by esterifying the 4-brom-G-chlor-phenylglycin-Q-carboxylic acid which can be produced by treating phenyl-glycin-Q-carboxylic acid first with bromin and then with chlorin) into a solution of twenty-three parts of sodium in seven hundred parts of methyl alcohol, and maintain the whole at seventy degrees centigrade for thirty minutes. Distil off the methyl alcohol, digest the residue with one thousand parts of water and two hundred parts of thirty per cent. acetic acid, and filter off and wash and dry the 5-brom- T-chlor-indoxyl carboxylic acid ester, which can be recrystallized from glacial acetic acid and thus be obtained in the form of long needles which melt at from about two hundred and three, to two hundred and five, degrees centigrade. The ester is insoluble Specification of Letters Patent Application filed September 30, 1909. Serial No. 520,351.

Patented Feb. 1, 1910.

. in water and is ditticultly soluble in most of the common organic solvents. It can be converted into the corresponding indigo coloring matter by boiling three hundred and four and one half parts of itwith five thousand parts of water and eleven hundred and forty-five parts of thirty-five per cent. caus tic soda for thirty minutes, while passing a current of coal gas through the.: solution. Then add seven thousand" parts ofboilin water to the mixture'and pass air throng it, at a temperature of zihoixt'one hundred degrees centigrade, until'the oxidation is complete. If desired,the saponification can be carried out intheabsence of coal gas, and instead of caustic soda, other saponifying agent, for instance caustic potash, can be employed. The dichlor-dibrom-indigo thus obtained dyes cotton, from the vat, brilliant blue shades. It is soluble in boiling dimethyl-anilin and cr stallizes from it in small blue needles. I e term it 7.7 -dichlor- ,5.5-dibrom-indigo. It possesses a constitution corresponding to the formula Now what we claim is v 1. As a new article of manufacture 7.7 dichlor-5.5'-dibrom-indigo, which is soluble in boiling dimethyl-anilin, which yields a blue solution in concentrated sulfuric acid, which dyes cotton blue, and which on oxidation by means of concentrated nitric acid in concentrated sulfuric acid solution yields 3-chlor-5-brom-isatoic acid, which acid melts and decomposes at a temperature of about 260 C.

2. The process of producing 7.7-dichlor- 5.5-dibrom-indigo by saponirying and oxidizing the methyl ester of 7-chlor-5--bromindoxylcarboxylic acid substantially as described.

In testimony whereof we have hereunto set our hands .in the presence of two subscribing witnesses.

PAUL ERIVI'N OBERREIT. VIKTOR VILLIGER. PAUL NAl/VIASKY. Witnesses: ERNEST F. EHRHARDT,

ERNEST L. Ives. 

